Since we're doing UI testing here, I was expecting that you'd also really try to click the start button. 

With FEST this can be done by
>         robot.click(robot.finder().findByName("jpacman.start"));

This also avoids the need to create your own button panel, simplifying the test.

This does call for making the name of the button `"jpacman.start"` available through a `public static String START_BUTTON_NAME` variable or something similar in the ButtonPanel class.